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The most-distant objects we can see are galaxies more than 13 billion light-years away. That means we see them as they looked just a few hundred million years after the Big Bang. We know their distance because astronomers measure their cosmological redshift — an effect caused by the expansion of the universe. As the universe expands, it “stretches” the wavelengths of light produced by stars and galaxies. The greater the distance, the more the light is stretched. Astronomers measure that effect by looking for the “barcodes” that different chemical elements imprint in the object’s light. Each barcode keeps the same pattern. But it appears at a different place in the object’s spectrum — the “rainbow” of colors produced when you break the light into its individual wavelengths. When an object is moving away from us, the patterns are shifted to longer wavelengths — toward the red end of the spectrum — the redshift. For galaxies that are especially far away, the wavelengths can be shifted into the infrared. But Earth’s atmosphere absorbs most infrared light. So the best way to study it is from space. But most telescopes in space aren’t big enough to see deeply into the universe, so they can’t see the earliest galaxies — or if they do see them, the galaxies look like fuzzy red blobs. Only one space telescope allows us to see those early galaxies as galaxies — Webb Space Telescope. More about that tomorrow.  Script by Damond Benningfield

During its four years of life, the InSight lander recorded more than 1300 “marsquakes.” Most of them were tiny, and most were caused by space rocks slamming into Mars. But the largest quake it ever felt came from the planet’s insides, far below the surface. That’s an indication that Mars isn’t dead yet. The quake took place in May of 2022, just a few months before InSight’s mission ended. It was magnitude 4.7. By Earth standards, that’s not much – maybe strong enough to feel, but not strong enough to cause any damage. But by Mars standards, it was a whopper – five times more powerful than the second-strongest quake. And it rattled around the planet for six hours. The quake was centered about 1400 miles away from InSight, in a region with a rugged surface. At first, scientists suspected the quake was caused by a large meteorite impact. That would’ve created a crater a thousand feet across, and blown away dust on the surface for miles around. So they scoured pictures taken by eight spacecraft in orbit around Mars. But they didn’t find a thing – no crater, no blast zone. That means the quake probably originated inside the planet, at a depth of about 11 to 17 miles. It might have been triggered by movement along a fault line. So even though the Martian crust isn’t made of moving plates, as Earth’s is, there may still be a good bit of shakin’ and rattlin’ below the surface of Mars.  Script by Damond Benningfield

Olympus Mons is the Mauna Loa of Mars. Like the mountain on the island of Hawaii, it’s the largest volcano on its planet —in this case, Mars. Also like Mauna Loa, it built up as molten rock bubbled through a “hotspot” in the crust. Finally, Olympus Mons might once have stood in the middle of an ocean. Olympus Mons is almost 13 miles high, and covers an area the size of France – much bigger than Mauna Loa. That’s because it never moved away from the hotspot, so it kept on building for billions of years. Today, it’s either dormant or extinct. It stands on a wide base that’s about four miles high, with sheer cliffs all around. A recent study says the top of the base shows evidence of contact with water. Scientists have already seen the possible shoreline of a shallow ocean. The ocean vanished long ago, as Mars grew colder and lost most of its air. The study found features along the rim of the Olympus Mons base that look like they formed when lava spilled into liquid water – supporting the idea of a long-gone ocean. So Olympus Mons might once have been not only the biggest volcano on Mars, but the biggest island as well. Mars is inching into the dawn sky. It’s quite close to the Sun, though, and it rises at a shallow angle. If you’re in Hawaii or southern Florida or Texas, you might spot it quite low in the southeast before sunrise. The rest of the U.S. won’t see it for a few weeks. More about Mars tomorrow.  Script by Damond Benningfield

El Gordo – the fat one – might not be the most flattering name for a galaxy cluster. But it’s certainly accurate. El Gordo is the most massive cluster yet seen that’s so far away – more than seven billion light-years. The cluster is actually two clusters that are ramming together. They contain hundreds of individual galaxies. They total about 2300 times the mass of our own galaxy, the Milky Way. Most of that mass consists of dark matter. It produces no detectable energy, but it reveals its presence through its gravitational pull on the visible matter around it. Astronomers measure the amount of dark matter by seeing how the cluster distorts the light of background galaxies. They know the mass of the visible parts of the galaxies. They subtract that from the cluster’s gravitational mass to calculate the amount of dark matter. El Gordo is so far away that we see it as it looked when the universe was a bit less than half its current age – about six-and-a-half billion years after the Big Bang. No other cluster at that distance or beyond is that heavy. So the cluster provides an excellent laboratory for studying galaxies and dark matter in the early universe. El Gordo is in Phoenix, the firebird. The constellation is so far south that it’s not visible from most of the United States – only Hawaii and southern Texas and Florida. From those locations, the firebird is low in the southern sky at nightfall.  Script by Damond Benningfield

During the Little Ice Age, much of the northern hemisphere was plunged into a deep freeze. Winters were so cold that the Thames River in England froze over, and the Vikings had to abandon their settlements in Greenland. Summers were chilly, rainy, and gloomy – perhaps helping inspire Mary Shelley to write “Frankenstein.” That era incorporates a time when the Sun was especially quiet. Known as the Maunder Minimum, it lasted from about 1645 to 1715. Astronomers recorded few sunspots then — they sometimes went months or years without seeing a single one. With less activity, the Sun emits less energy. That suggests the Sun could be at least partially responsible for the Little Ice Age. A recent study found that not only was the Sun especially quiet during that era, but its cycle of magnetic activity was especially short. At the peak of a solar cycle, the Sun is covered with many sunspots, and it produces big explosions of gas and energy. The cycle lasts an average of about 11 years, although it can vary by a couple of years either way. The study found that the cycles during the Maunder Minimum lasted only about eight years. Researchers looked at records of auroras kept by Korean astronomers. Auroras are created by particles from the Sun, so their intensity and location can reveal the Sun’s activity level. The study found a clear eight-year cycle in the records – a short cycle during an era that was short on warmth.  Script by Damond Benningfield